Bag of Vermin (3.5e Equipment)

From D&D Wiki

These unpleasant looking, mottled cloth bags seem to writhe about perpetually, as if something alive were contained within them. Like a bag of holding, a bag of vermin is a tiny self-contained dimension, but instead of storing items, bags of vermin bring forth swarms of a single specific type. When opened, one swarm pours forth from the bag each round until the bag empties or is closed. A bag of vermin can contain a maximum of five swarms of its type and replenishes its contents at a rate of one swarm every minute. Each swarm remains for one hour after which it dissipates.

Swarms conjured by a bag of virmin will not attack the bag's user. Although the swarms cannot be compelled to attack or not to attack certain creatures, the person that holds the bag can mentally command the swarm to move to any location he desires. Because a swarm automatically attacks the creatures with which it shares its square, guiding the swarms to move is the same as guiding the swarms to attack certain creatures.